XMLDA.NET Sample Application

Visual Basic Windows Forms Application that uses DataBind subscriptions

A CheckBox, a ProgressBar and a ListView are updated with item values from an OPC-DA or XML-DA server. Three DataBind subsriptions are defined. A binary value is assigned to the CheckBox, an integer value to the ProgressBar and an array of double to the ListBox.

   Dim OpcSrv As XmlServer = Nothing

   Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
      If Not OpcSrv Is Nothing Then
         Return
      End If
      tbStatus.Text = ""
      ListView1.Items.Clear()
      ListView1.Items.Add("")
      ListView1.Items.Add("")
      Try
         OpcSrv = New XmlServer(Me.cbOPCServers.Text)
         ' build an ArrayList with dataBind definitions
         Dim subscr As DataBindSubscription()
         ReDim subscr(2)
         subscr(0) = New DataBindSubscription("SimulatedData.Signal", Me.CheckBox1)
         subscr(1) = New DataBindSubscription("SimulatedData.Ramp", Me.ProgressBar1)
         subscr(2) = New DataBindSubscription("Dynamic.Analog Types.Double[]", Me.ListView1.Items(1).SubItems)
         Dim err As OPCError()
         OpcSrv.DataBindSubscribe(Me, subscr, 1000, Nothing, err)
         tbStatus.Text = "Started"
      Catch ex As Exception
         tbStatus.Text = ex.Message
         OpcSrv = Nothing
      End Try
   End Sub

   Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
      If Not OpcSrv Is Nothing Then
         Dim err As OPCError()
         OpcSrv.DataBindCancel(Nothing, Nothing, err)
         OpcSrv = Nothing
         tbStatus.Text = "Stopped"
      End If
   End Sub